Toshiba 37 inch tv?

the-wizard here again...

Hm??? Top left and bottom right.
Top left and bottom right...
That doesn't sound like shadow mask.
It sounds a bit too symetrical.

I would look at the purity magnet settings on the neck of the tube to see if one has slipped. NOTE make sure that you not the postion of a tab if you do slide it around and return it before moving another one. Get these buddies mixed up too much from their factory settings and you're in real doggy doo doo.

Note. These 37inch toshiba 4: tubes were hand made and the guns, outgassing and pumping was of the very best available quality available in the world. If this issue can be resolved there's no reason why the tube shouldn't outlive every other functioning component in the set.

Good luck twiddling your purity mags if the degausser doesn't work. But be carefull!!!

the-wizard
July 2005

Get yourself a degausser from a TV service engineer.

It's a piece of kit you hover around the screen pulling it back gradually.


If this doesn't work then cobwebs suggestion of warped shadowmask is probably the case in which replacement may prove to be tricky. 4:3 ratio 37 inch CRTs are definately out of production and like rocking horse sh*t to obtain.

the-wizard

the-wizard
July 2005

Assuming this is a TV with a cathode ray tube;
Most likely, the shadowmask (a thin sheet of metal immediately behind the galss tube face) has become magnetized.

Usually this is simply from the earth magnetic field but can be caused by any magnetism in close proximity to the TV. (eg. loudspeakers contain large magnets). Also, moving the position of the TV can create/alter the effect, or proximity of large metal objects (central heating radiators).

Though most commonly it's due to failure of a component called a positor (part the TV's own automatic demagnetizing circuit).
These are very cheap and it is usually one of the least expensive of common TV repairs & a 10 minute repair.

Extrememly rarely, the problem is caused by mechanical shock to the shadowmask causing it to warp or become dislodged. That would require replacement of the cathode ray tube (tube).

A service engineer may manually degauss the TV and/or the surrounding area if the problem is persistent.

Cobweb
June 2005